Litchi toxin causes AES, says Vellore doc’s study

PATNA: Even as consensus has eluded researchers for years on the cause of Acute Encephalitis Syndrome (AES) which has claimed several children’s lives in Muzaffapur district of Bihar, Vellore-based paediatrician and epidemiologist Dr T Jacob John has now said a toxin in litchi causes the disease. The study by Dr John was commissioned by the Bihar government. Earlier, US-based Centre for Disease Control (CDC) had said that Jamaican Ackee – a fruit resembling litchi – is known to have a toxin that causes AES-type disease in African nations. Even though Dr John is yet to submit his report to the Bihar government, the findings have been published in the recent edition of Current Science, a journal of Indian Institute of Science, Bangalore. The paper is jointly authored by Dr John and Arun Shah of Indian Institute of Toxicology Research-Lucknow. Responding to TOI’s emailed queries, Dr John said, “The CDC research of 2013 said litchi seeds contain a toxin that causes hypoglycaemia; that is, fall in sugar level. However, children seldom swallow seeds. They swallow litchi fruits, hence it (the cause) remained a mystery. Our research confirmed both ripe and semi-ripe litchis contain a toxin called methylene cyclopropyl-glycine (MCPG) that causes hypoglycaemia in children, which leads to death.” The paper contains a table which shows the highest amount of MCPG is found in litchi seeds, followed by semi-ripe and ripe litchi fruits. The paper also clarifies AES is not encephalitis, but encephalopathy. In encephalitis, brain is primarily affected due to viral infection. In encephalopathy, brain is “secondarily affected” and not by a virus. Dr John has termed the disease as ‘hypoglycaemic encephalopathy’. However, AES is also killing children in Gorakhpur (UP) and Malda (West Bengal), where they are not exposed to litchis. To this, Dr John replied his research is based only on Muzaffarpur kids. “The AES of Gorakhpur remains to be diagnosed. There is no litchi connection in Gorakhpur. In Malda, however, there are litchi orchards, and what is called AES there could be ‘hypoglycaemic encephalopathy’,” he said. According to the State Health Society of Bihar, the number of AES cases in 2015 was 390 compared to 1,028 in 2014. In this regard, Dr John said, “In 2015, the litchi yield was apparently low. Besides, the health department spread awareness that children shouldn’t go to sleep without meal as this could lead to hypoglycaemia. Supervision by adults on litchi consumption is another factor.”

Muzaffarpur-based Sri Krishna Medical College and Hospital’s paediatrics HoD Dr Braj Mohan agrees with Dr John’s research, but with a caveat. Dr Mohan, who has years of experience of treating AES-affected kids and who was earlier critical of the litchi theory, said, “I would add that the kids who have a compromised liver and/or are malnourished are more susceptible to the litchi toxin.” AIIMS-Patna has a different view AIIMS-Patna director G K Singh said his institute’s findings also showed 64 AES-hit patients suffered from hypoglycaemia. “But whether hypoglycaemia was the cause or the effect of AES is yet to be established,” he told TOI, adding 60% AES-hit patients in Muzaffarpur did not have any exposure to litchi. Dr Singh stuck to his institute’s theory that it is a water-borne disease and children are being infected by a virus carried through the Saryu in UP and Bihar. The Saryu’s contaminated matter reaches the Ganga in Chhapra and then to the Gandak, which crosses Muzaffarpur. “Better sanitation for prevention of transmission of virus through faeco-oral route is the key (to AES control). Based on this hypothesis, measures taken by the state government to provide safe drinking water led to fall in the number of AES cases in 2015,” Dr Singh told TOI.